Processed fish-egg products include: cod roe using cod eggs as a raw material; spicy cod roe; trout roe using trout eggs as a raw material; salmon caviar or salmon roe using salmon eggs as a raw material; flying fish roe using flying-fish eggs as a raw material; botargo using mullet or tuna eggs as a raw material; caviar using sturgeon eggs as a raw material; herring roe using herring eggs as a raw material; and kouruka using sweetfish eggs as a raw material. Those processed fish-egg products are generally shipped after increasing their product storage lives by salting the raw material fish eggs. In addition, spicy cod roe, for example, may include a salting processing step by immersion in saline and an aging step of aging after soaking in a flavoring solution.
The color tone, texture, taste, and the like of the processed fish-egg products have an effect on the level of the product quality. For this reason, processes to brighten the color tone of cod roe, spicy cod roe, salmon caviar, salmon roe, or the like are performed, for example, by adding color-developing agents such as nitrites to the raw material fish eggs.
However, nitrites which are often used as the color-developing agents react with amines contained in the fish eggs in a large amount to produce N-nitrosamines. The N-nitrosamines is pointed out as being carcinogenic.
As a result, various proposals have been made for improving the color tone of the fish eggs without uses of color-developing agents such as nitrites.
For example, in Patent Document 1 described below, there is disclosed a method of preventing color loss in fish eggs, which is characterized in that a yeast treatment material is added to the fish eggs.
Further, in Patent Document 2 described below, use amount of the nitrites is reduced by use of ferulic acid and nicotinic-acid amide as a color-developing aid.
Further, in Patent Document 3 described below, a method of manufacturing spicy cod roe is disclosed, the method including a salting step by soaking cod eggs in saline and an aging step by aging after soaking the cod eggs in a flavoring solution. The method is characterized in that the salt used in the saline in the salting step is a salt mixed with a Sasa veitchii component.
On the other hand, the inventors of the present invention have proposed, in Patent Document 4 described below, a method of improving the color tone of meat or fish containing red-pigment proteins through addition of microorganisms belonging to the genus Carnobacterium or Lactobacillus.     Patent Document 1: JP 2000-245400 A    Patent Document 2: JP 2000-325049 A    Patent Document 3: JP 2004-283131 A    Patent Document 4: JP 2006-166815 A